SiOx Tridymite Carbon Coated Anode for Battery Capacity
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in maintaining cycle performance and battery capacity due to the expansion and contraction of silicon-based negative electrode active materials, leading to electrolyte decomposition and reduced cycle life.
Innovation Solution
A negative electrode material comprising silicon oxide (SiOx) with a tridymite structure coated with a carbon layer, where 0.5≤x≤1.6, is developed, which improves conductivity and reduces irreversible capacity through effective lithium insertion and extraction modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as negative electrode active material to improve battery capacity, then battery capacity increases, but cycle performance deteriorates due to expansion and contraction causing particle breakage and electrolyte decomposition
Solution Approach 1:
The patent applies nested structure by placing silicon particles inside a carbon coating layer, forming a core-shell structure where the carbon layer encapsulates the silicon active material. This nesting protects the silicon from direct contact with electrolyte while maintaining its electrochemical activity, thereby improving cycle performance without sacrificing capacity.
Solution Approach 2:
The patent creates a composite material system combining silicon and carbon in a specific structure. The carbon coating layer (0.5-5 μm thickness) forms a composite structure with the silicon core, providing both mechanical strength to prevent breakage and chemical stability to prevent electrolyte decomposition, while the silicon core provides high capacity.
2Quantity of substance
If silicon active material is used to increase battery capacity, then capacity improves, but electrolyte decomposition increases due to new surface creation from particle breakage
Solution Approach 1:
The patent extracts the harmful surface of silicon particles by coating them with carbon, effectively removing the direct interface between silicon and electrolyte. The carbon layer acts as a barrier that prevents electrolyte contact with the silicon surface, thereby eliminating the source of decomposition reactions while preserving the electrochemical functionality.
Solution Approach 2:
The carbon coating layer serves as an intermediary substance between silicon and electrolyte. It mediates the interaction by providing a stable interface that allows ionic transport while preventing direct chemical reactions between electrolyte and silicon, thus reducing electrolyte decomposition.
3Reliability
If carbon coating layer is applied to silicon particles to improve cycle performance, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges for the carbon coating layer (thickness: 0.5-5 μm, carbon content: 5-50 at%) to optimize performance while managing complexity. By defining clear parameter boundaries, the invention transforms a complex manufacturing challenge into a controllable process with measurable targets.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances battery performance by maintaining capacity retention and initial efficiency, preventing electrolyte decomposition, and improving the safety and electrical conductivity of the battery.
Implementation Method 1
improves conductivity of the negative electrode active material particles
Implementation Method 2
effective lithium insertion and extraction modifications
Data Source
Figure 1~2
Figure 3
AI summary
The present invention is a negative electrode material for a non-aqueous electrolyte secondary battery, including negative electrode active material particles containing a silicon compound expressed by SiOx where 0.5≤x≤1.6, the silicon compound being coated with a carbon coating layer composed of a carbon component, wherein the negative electrode active material particles contain a SiO2 component having a tridymite structure and exhibit a diffraction peak around 21.825° with a half width (2θ) of 0.15° or less in X-ray diffraction. This negative electrode material for a non-aqueous electrolyte secondary battery can increase the battery capacity and improve the cycle performance and the initial charge and discharge performance.